It’s been a slow-motion train wreck.
Twenty-six years ago, the US eliminated endemic transmission one of the world’s most contagious diseases, thanks largely to the development and widespread use of a highly effective vaccine.
But now, that hard-won victory is unraveling. The virus once pushed out of circulation has roared back to life, fueling a growing wave of illnesses and threatening to strip the country of a public health milestone that took decades to achieve.
Next week, a PAHO commission is scheduled to meet in Washington, D.C., to consider whether the US should lose its measles elimination status.
The independent panel, made up of experts in epidemiology, public health, virology, pediatrics and immunization, will examine whether measles has been spreading continuously in the US for at least 12 months — the benchmark for determining that the disease is once again endemic.
So far, the signs aren’t encouraging.
A New York Times investigation found that several chains of measles transmission appear to have persisted for more than a year, based on publicly available genetic data analyzed by scientists ahead of the meeting.
For example, three separate chains of transmission were still active in July 2026 — two in Utah and one in Arizona. All three could be traced back to an outbreak in Texas more than a year earlier.
One of those chains continued spreading in Utah through September, occasionally crossing into neighboring Oregon and Washington.
“This alone is strong evidence that there has been ongoing transmission for over a year,” Bill Hanage, co-director of the Center for Communicable Disease Dynamics at Harvard’s T.H. Chan School of Public Health, told the Times.
The comeback isn’t happening out of the blue.
In 2026 alone, the US has reported 5,182 confirmed cases — the highest annual total in 35 years, and more than double the number recorded in all of 2025, according to the CDC.
At least 562 people, or roughly 11% of those infected, have been hospitalized. Eight people have died, including an unvaccinated infant in New York.
Congenital measles, in which an infected mother passes the virus to her newborn, is also again being reported.
How we eliminated measles in the first place
Before the measles vaccine was introduced in 1963, the virus was a near-inevitability of childhood in the US. An estimated 3 million to 4 million Americans caught it every year, and hundreds died.
But the shot changed all that. Over the decades that followed, widespread immunization drove infections down until, in 2000, the Pan American Health Organization (PAHO) declared measles eliminated in the US.
That didn’t mean the virus had disappeared entirely, but that it was no longer spreading continuously within the country’s borders for 12 months or longer.
Cases still cropped up, usually when an unvaccinated traveler caught measles overseas and brought it home. But health officials were generally able to stop those outbreaks from spreading further, thanks to rapid response efforts and high vaccination rates in surrounding communities.
That firewall, however, appears to be crumbling.
Plunging vaccine rates bring measles back to the forefront
Vaccination rates have steadily slipped in recent years, leaving more children vulnerable to infection and making it easier for outbreaks to take hold.
Just 92.4% of kindergartners had received the measles, mumps and rubella (MMR) vaccine during the 2025-2026 school year — below the 95% coverage that the CDC says is generally needed to maintain community protection against measles.
The shift comes amid rising skepticism among Americans about the safety and effectiveness of measles vaccines and a decline in trust of public health authorities in general.
Against this backdrop, several epidemiologists and infectious disease doctors told CIDRAP News they believe PAHO is likely to declare measles endemic in the US.
“It’s a symbolic loss,” Dr. Jennifer Nuzzo, director of Brown University’s Pandemic Center, told the outlet. “It’s a loss of standing. It’s a loss of stature. It’s a loss of achievement.”
But the damage isn’t irreversible. The experts said a renewed push to boost vaccination rates could help stop measles from spreading and eventually restore the country’s measles-free status, if PAHO revokes it.
Brazil has already shown it’s possible. After losing its status in 2019, the country got it back in 2024 by ramping up targeted vaccination campaigns and strengthening disease surveillance.
The PAHO panel is expected to announce its decision by November 17, according to the Times.
